Clinical features and outcomes of aspiration pneumonia compared with non-aspiration pneumonia: a retrospective cohort study.

Pneumonia is a leading cause of death among elderly patients. Although aspiration pneumonia (AP) commonly occurs with aging, its clinical features and outcomes are still uncertain. The aims of this study were to describe the clinical features and outcomes of AP and to assess whether presence of AP affects clinical outcomes in patients with community-acquired pneumonia (CAP) and healthcare-associated pneumonia (HCAP). We retrospectively analyzed patients with CAP and HCAP hospitalized in our institution in Japan from October 2010 to March 2012. We compared clinical features and outcomes between AP and non-AP, and investigated risk factors for recurrence of pneumonia and death. Of 214 consecutive patients, 100 (46.7%) were diagnosed as having aspiration pneumonia. These patients were older and had lower body mass index, more comorbidities, and poorer Eastern Cooperative Oncology Group performance status (ECOG PS) than the patients with non-AP. Patients with AP had more severe disease, required longer hospital stays, and had a frequent recurrence rate of pneumonia and higher mortality. In multivariate analyses, AP, age, and ECOG PS were related to recurrence of pneumonia, and the prognostic factors were CURB-65 score and ECOG PS. AP was not a significant indicator for prognosis but was the strongest risk factor for recurrence of pneumonia. Clinical background and outcomes including recurrence and mortality of AP were obviously different from those of non-AP; therefore AP should be considered as a distinct subtype of pneumonia, and it is important to prevent the recurrence of pneumonia in the patients with AP.